This report presents information on determinants of blood pressure variation in a rural sample of 263 Ethiopian highlanders 14-86 years of age, resident at 3530 m on the Simien Plateau. Mean systolic and diastolic blood pressures for males and females were 109/ 75 and 106/73, respectively, and there were no age differences. These findings confirmed that men and women can have low normal blood pressure throughout adulthood. Blood pressures increased with increasing body mass index (BMI) among adult males, although the mean BMI of 19.1 kg/m2 was low compared with US values. This illustrates that BMI variation may be associated with blood pressure variation in men even at low mean values of both. Blood pressure did not vary with adult haemoglobin concentration.